<?php


// +----------------------------------------------------------------------+
// | PHP versions 4 and 5                                                 |
// +----------------------------------------------------------------------+
// | Copyright (c) 1998-2006 Manuel Lemos, Tomas V.V.Cox,                 |
// | Stig. S. Bakken, Lukas Smith                                         |
// | All rights reserved.                                                 |
// +----------------------------------------------------------------------+
// | MDB2 is a merge of PEAR DB and Metabases that provides a unified DB  |
// | API as well as database abstraction for PHP applications.            |
// | This LICENSE is in the BSD license style.                            |
// |                                                                      |
// | Redistribution and use in source and binary forms, with or without   |
// | modification, are permitted provided that the following conditions   |
// | are met:                                                             |
// |                                                                      |
// | Redistributions of source code must retain the above copyright       |
// | notice, this list of conditions and the following disclaimer.        |
// |                                                                      |
// | Redistributions in binary form must reproduce the above copyright    |
// | notice, this list of conditions and the following disclaimer in the  |
// | documentation and/or other materials provided with the distribution. |
// |                                                                      |
// | Neither the name of Manuel Lemos, Tomas V.V.Cox, Stig. S. Bakken,    |
// | Lukas Smith nor the names of his contributors may be used to endorse |
// | or promote products derived from this software without specific prior|
// | written permission.                                                  |
// |                                                                      |
// | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS  |
// | "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT    |
// | LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS    |
// | FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE      |
// | REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,          |
// | INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
// | BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS|
// |  OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED  |
// | AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT          |
// | LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY|
// | WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE          |
// | POSSIBILITY OF SUCH DAMAGE.                                          |
// +----------------------------------------------------------------------+
// | Author: Lukas Smith <smith@pooteeweet.org>                           |
// +----------------------------------------------------------------------+
//
// $Id: Common.php,v 1.112 2006/10/14 13:42:00 lsmith Exp $

require_once 'Class/Lib/MDB2/LOB.php';
/**
 * @package  MDB2
 * @category Database
 * @author   Lukas Smith <smith@pooteeweet.org>
 */

/**
 * MDB2_Driver_Common: Base class that is extended by each MDB2 driver
 *
 * @package MDB2
 * @category Database
 * @author Lukas Smith <smith@pooteeweet.org>
 */
class MDB2_Driver_Datatype_Common extends MDB2_Module_Common
{
	var $valid_default_values = array(
        'text'      => '',
        'boolean'   => true,
        'integer'   => 0,
        'decimal'   => 0.0,
        'float'     => 0.0,
        'timestamp' => '1970-01-01 00:00:00',
        'time'      => '00:00:00',
        'date'      => '1970-01-01',
        'clob'      => '',
        'blob'      => '',
	);

	/**
	 * contains all LOB objects created with this MDB2 instance
	 * @var array
	 * @access protected
	 */
	var $lobs = array();

	// }}}
	// {{{ getValidTypes()

	/**
	 * Get the list of valid types
	 *
	 * This function returns an array of valid types as keys with the values
	 * being possible default values for all native datatypes and mapped types
	 * for custom datatypes.
	 *
	 * @return mixed array on success, a MDB2 error on failure
	 * @access public
	 */
	function getValidTypes()
	{
		$types = $this->valid_default_values;
		$db =& $this->getDBInstance();
		if (PEAR::isError($db)) {
			return $db;
		}
		if (!empty($db->options['datatype_map'])) {
			foreach ($db->options['datatype_map'] as $type => $mapped_type) {
				if (array_key_exists($mapped_type, $types)) {
					$types[$type] = $types[$mapped_type];
				} elseif (!empty($db->options['datatype_map_callback'][$type])) {
					$parameter = array('type' => $type, 'mapped_type' => $mapped_type);
					$default =  call_user_func_array($db->options['datatype_map_callback'][$type], array(&$db, __FUNCTION__, $parameter));
					$types[$type] = $default;
				}
			}
		}
		return $types;
	}

	// }}}
	// {{{ checkResultTypes()

	/**
	 * Define the list of types to be associated with the columns of a given
	 * result set.
	 *
	 * This function may be called before invoking fetchRow(), fetchOne()
	 * fetchCole() and fetchAll() so that the necessary data type
	 * conversions are performed on the data to be retrieved by them. If this
	 * function is not called, the type of all result set columns is assumed
	 * to be text, thus leading to not perform any conversions.
	 *
	 * @param string $types array variable that lists the
	 *       data types to be expected in the result set columns. If this array
	 *       contains less types than the number of columns that are returned
	 *       in the result set, the remaining columns are assumed to be of the
	 *       type text. Currently, the types clob and blob are not fully
	 *       supported.
	 * @return mixed MDB2_OK on success, a MDB2 error on failure
	 * @access public
	 */
	function checkResultTypes($types)
	{
		$types = is_array($types) ? $types : array($types);
		foreach ($types as $key => $type) {
			if (!isset($this->valid_default_values[$type])) {
				$db =& $this->getDBInstance();
				if (PEAR::isError($db)) {
					return $db;
				}
				if (empty($db->options['datatype_map'][$type])) {
					return $db->raiseError(MDB2_ERROR_UNSUPPORTED, null, null,
					$type.' for '.$key.' is not a supported column type', __FUNCTION__);
				}
			}
		}
		return $types;
	}

	// }}}
	// {{{ _baseConvertResult()

	/**
	 * general type conversion method
	 *
	 * @param mixed $value refernce to a value to be converted
	 * @param string $type specifies which type to convert to
	 * @return object a MDB2 error on failure
	 * @access protected
	 */
	function _baseConvertResult($value, $type, $rtrim = true)
	{
		switch ($type) {
			case 'text':
				if ($rtrim) {
					$value = rtrim($value);
				}
				return $value;
			case 'integer':
				return intval($value);
			case 'boolean':
				return !empty($value);
			case 'decimal':
				return $value;
			case 'float':
				return doubleval($value);
			case 'date':
				return $value;
			case 'time':
				return $value;
			case 'timestamp':
				return $value;
			case 'clob':
			case 'blob':
				$this->lobs[] = array(
                'buffer' => null,
                'position' => 0,
                'lob_index' => null,
                'endOfLOB' => false,
                'resource' => $value,
                'value' => null,
                'loaded' => false,
				);
				end($this->lobs);
				$lob_index = key($this->lobs);
				$this->lobs[$lob_index]['lob_index'] = $lob_index;
				return fopen('MDB2LOB://'.$lob_index.'@'.$this->db_index, 'r+');
		}

		$db =& $this->getDBInstance();
		if (PEAR::isError($db)) {
			return $db;
		}

		return $db->raiseError(MDB2_ERROR_INVALID, null, null,
            'attempt to convert result value to an unknown type :' . $type, __FUNCTION__);
	}

	// }}}
	// {{{ convertResult()

	/**
	 * convert a value to a RDBMS indepdenant MDB2 type
	 *
	 * @param mixed $value value to be converted
	 * @param string $type specifies which type to convert to
	 * @param bool   $rtrim   if to rtrim text values or not
	 * @return mixed converted value
	 * @access public
	 */
	function convertResult($value, $type, $rtrim = true)
	{
		if (is_null($value)) {
			return null;
		}
		$db =& $this->getDBInstance();
		if (PEAR::isError($db)) {
			return $db;
		}
		if (!empty($db->options['datatype_map'][$type])) {
			$type = $db->options['datatype_map'][$type];
			if (!empty($db->options['datatype_map_callback'][$type])) {
				$parameter = array('type' => $type, 'value' => $value, 'rtrim' => $rtrim);
				return call_user_func_array($db->options['datatype_map_callback'][$type], array(&$db, __FUNCTION__, $parameter));
			}
		}
		return $this->_baseConvertResult($value, $type, $rtrim);
	}

	// }}}
	// {{{ convertResultRow()

	/**
	 * convert a result row
	 *
	 * @param array $types
	 * @param array $row specifies the types to convert to
	 * @param bool   $rtrim   if to rtrim text values or not
	 * @return mixed MDB2_OK on success,  a MDB2 error on failure
	 * @access public
	 */
	function convertResultRow($types, $row, $rtrim = true)
	{
		reset($types);
		$current_column = -1;
		foreach ($row as $key => $value) {
			++$current_column;
			if (!isset($value)) {
				continue;
			}
			if (isset($types[$current_column])) {
				$type = $types[$current_column];
			} elseif (isset($types[$key])) {
				$type = $types[$key];
			} elseif (current($types)) {
				$type = current($types);
				next($types);
			} else {
				continue;
			}
			$value = $this->convertResult($row[$key], $type, $rtrim);
			if (PEAR::isError($value)) {
				return $value;
			}
			$row[$key] = $value;
		}
		return $row;
	}

	// }}}
	// {{{ getDeclaration()

	/**
	 * Obtain DBMS specific SQL code portion needed to declare
	 * of the given type
	 *
	 * @param string $type type to which the value should be converted to
	 * @param string  $name   name the field to be declared.
	 * @param string  $field  definition of the field
	 * @return string  DBMS specific SQL code portion that should be used to
	 *                 declare the specified field.
	 * @access public
	 */
	function getDeclaration($type, $name, $field)
	{
		$db =& $this->getDBInstance();
		if (PEAR::isError($db)) {
			return $db;
		}

		if (!empty($db->options['datatype_map'][$type])) {
			$type = $db->options['datatype_map'][$type];
			if (!empty($db->options['datatype_map_callback'][$type])) {
				$parameter = array('type' => $type, 'name' => $name, 'field' => $field);
				return call_user_func_array($db->options['datatype_map_callback'][$type], array(&$db, __FUNCTION__, $parameter));
			}
		}

		if (!method_exists($this, "_get{$type}Declaration")) {
			return $db->raiseError(MDB2_ERROR_NOT_FOUND, null, null,
                'type not defined: '.$type, __FUNCTION__);
		}
		return $this->{"_get{$type}Declaration"}($name, $field);
	}

	// }}}
	// {{{ getTypeDeclaration()

	/**
	 * Obtain DBMS specific SQL code portion needed to declare an text type
	 * field to be used in statements like CREATE TABLE.
	 *
	 * @param array $field  associative array with the name of the properties
	 *      of the field being declared as array indexes. Currently, the types
	 *      of supported field properties are as follows:
	 *
	 *      length
	 *          Integer value that determines the maximum length of the text
	 *          field. If this argument is missing the field should be
	 *          declared to have the longest length allowed by the DBMS.
	 *
	 *      default
	 *          Text value to be used as default for this field.
	 *
	 *      notnull
	 *          Boolean flag that indicates whether this field is constrained
	 *          to not be set to null.
	 * @return string  DBMS specific SQL code portion that should be used to
	 *      declare the specified field.
	 * @access public
	 */
	function getTypeDeclaration($field)
	{
		$db =& $this->getDBInstance();
		if (PEAR::isError($db)) {
			return $db;
		}

		switch ($field['type']) {
			case 'text':
				$length = !empty($field['length']) ? $field['length'] : $db->options['default_text_field_length'];
				$fixed = !empty($field['fixed']) ? $field['fixed'] : false;
				return $fixed ? ($length ? 'CHAR('.$length.')' : 'CHAR('.$db->options['default_text_field_length'].')')
				: ($length ? 'VARCHAR('.$length.')' : 'TEXT');
			case 'clob':
				return 'TEXT';
			case 'blob':
				return 'TEXT';
			case 'integer':
				return 'INT';
			case 'boolean':
				return 'INT';
			case 'date':
				return 'CHAR ('.strlen('YYYY-MM-DD').')';
			case 'time':
				return 'CHAR ('.strlen('HH:MM:SS').')';
			case 'timestamp':
				return 'CHAR ('.strlen('YYYY-MM-DD HH:MM:SS').')';
			case 'float':
				return 'TEXT';
			case 'decimal':
				return 'TEXT';
		}
		return '';
	}

	// }}}
	// {{{ _getDeclaration()

	/**
	 * Obtain DBMS specific SQL code portion needed to declare a generic type
	 * field to be used in statements like CREATE TABLE.
	 *
	 * @param string $name   name the field to be declared.
	 * @param array  $field  associative array with the name of the properties
	 *      of the field being declared as array indexes. Currently, the types
	 *      of supported field properties are as follows:
	 *
	 *      length
	 *          Integer value that determines the maximum length of the text
	 *          field. If this argument is missing the field should be
	 *          declared to have the longest length allowed by the DBMS.
	 *
	 *      default
	 *          Text value to be used as default for this field.
	 *
	 *      notnull
	 *          Boolean flag that indicates whether this field is constrained
	 *          to not be set to null.
	 *      charset
	 *          Text value with the default CHARACTER SET for this field.
	 *      collation
	 *          Text value with the default COLLATION for this field.
	 * @return string  DBMS specific SQL code portion that should be used to
	 *      declare the specified field.
	 * @access protected
	 */
	function _getDeclaration($name, $field)
	{
		$db =& $this->getDBInstance();
		if (PEAR::isError($db)) {
			return $db;
		}

		$default = '';
		if (array_key_exists('default', $field)) {
			if ($field['default'] === '') {
				$field['default'] = empty($field['notnull'])
				? null : $this->valid_default_values[$field['type']];
				if ($field['default'] === ''
				&& ($db->options['portability'] & MDB2_PORTABILITY_EMPTY_TO_NULL)
				) {
					$field['default'] = ' ';
				}
			}
			$default = ' DEFAULT '.$this->quote($field['default'], $field['type']);
		} elseif (empty($field['notnull'])) {
			$default = ' DEFAULT NULL';
		}

		$charset = empty($field['charset']) ? '' :
            ' '.$this->_getCharsetFieldDeclaration($field['charset']);

		$collation = empty($field['collation']) ? '' :
            ' '.$this->_getCollationFieldDeclaration($field['collation']);

		$notnull = empty($field['notnull']) ? '' : ' NOT NULL';
		$name = $db->quoteIdentifier($name, true);
		return $name.' '.$this->getTypeDeclaration($field).$charset.$default.$notnull.$collation;
	}

	// }}}
	// {{{ _getCharsetFieldDeclaration()

	/**
	 * Obtain DBMS specific SQL code portion needed to set the CHARACTER SET
	 * of a field declaration to be used in statements like CREATE TABLE.
	 *
	 * @param string $charset   name of the charset
	 * @return string  DBMS specific SQL code portion needed to set the CHARACTER SET
	 *                 of a field declaration.
	 */
	function _getCharsetFieldDeclaration($charset)
	{
		return '';
	}

	// }}}
	// {{{ _getCollationFieldDeclaration()

	/**
	 * Obtain DBMS specific SQL code portion needed to set the COLLATION
	 * of a field declaration to be used in statements like CREATE TABLE.
	 *
	 * @param string $collation   name of the collation
	 * @return string  DBMS specific SQL code portion needed to set the COLLATION
	 *                 of a field declaration.
	 */
	function _getCollationFieldDeclaration($collation)
	{
		return '';
	}

	// }}}
	// {{{ _getIntegerDeclaration()

	/**
	 * Obtain DBMS specific SQL code portion needed to declare an integer type
	 * field to be used in statements like CREATE TABLE.
	 *
	 * @param string $name name the field to be declared.
	 * @param array $field associative array with the name of the properties
	 *       of the field being declared as array indexes. Currently, the types
	 *       of supported field properties are as follows:
	 *
	 *       unsigned
	 *           Boolean flag that indicates whether the field should be
	 *           declared as unsigned integer if possible.
	 *
	 *       default
	 *           Integer value to be used as default for this field.
	 *
	 *       notnull
	 *           Boolean flag that indicates whether this field is constrained
	 *           to not be set to null.
	 * @return string DBMS specific SQL code portion that should be used to
	 *       declare the specified field.
	 * @access protected
	 */
	function _getIntegerDeclaration($name, $field)
	{
		if (!empty($field['unsigned'])) {
			$db =& $this->getDBInstance();
			if (PEAR::isError($db)) {
				return $db;
			}

			$db->warnings[] = "unsigned integer field \"$name\" is being declared as signed integer";
		}
		return $this->_getDeclaration($name, $field);
	}

	// }}}
	// {{{ _getTextDeclaration()

	/**
	 * Obtain DBMS specific SQL code portion needed to declare an text type
	 * field to be used in statements like CREATE TABLE.
	 *
	 * @param string $name name the field to be declared.
	 * @param array $field associative array with the name of the properties
	 *       of the field being declared as array indexes. Currently, the types
	 *       of supported field properties are as follows:
	 *
	 *       length
	 *           Integer value that determines the maximum length of the text
	 *           field. If this argument is missing the field should be
	 *           declared to have the longest length allowed by the DBMS.
	 *
	 *       default
	 *           Text value to be used as default for this field.
	 *
	 *       notnull
	 *           Boolean flag that indicates whether this field is constrained
	 *           to not be set to null.
	 * @return string DBMS specific SQL code portion that should be used to
	 *       declare the specified field.
	 * @access protected
	 */
	function _getTextDeclaration($name, $field)
	{
		return $this->_getDeclaration($name, $field);
	}

	// }}}
	// {{{ _getCLOBDeclaration()

	/**
	 * Obtain DBMS specific SQL code portion needed to declare an character
	 * large object type field to be used in statements like CREATE TABLE.
	 *
	 * @param string $name name the field to be declared.
	 * @param array $field associative array with the name of the properties
	 *        of the field being declared as array indexes. Currently, the types
	 *        of supported field properties are as follows:
	 *
	 *        length
	 *            Integer value that determines the maximum length of the large
	 *            object field. If this argument is missing the field should be
	 *            declared to have the longest length allowed by the DBMS.
	 *
	 *        notnull
	 *            Boolean flag that indicates whether this field is constrained
	 *            to not be set to null.
	 * @return string DBMS specific SQL code portion that should be used to
	 *        declare the specified field.
	 * @access public
	 */
	function _getCLOBDeclaration($name, $field)
	{
		$db =& $this->getDBInstance();
		if (PEAR::isError($db)) {
			return $db;
		}

		$notnull = empty($field['notnull']) ? '' : ' NOT NULL';
		$name = $db->quoteIdentifier($name, true);
		return $name.' '.$this->getTypeDeclaration($field).$notnull;
	}

	// }}}
	// {{{ _getBLOBDeclaration()

	/**
	 * Obtain DBMS specific SQL code portion needed to declare an binary large
	 * object type field to be used in statements like CREATE TABLE.
	 *
	 * @param string $name name the field to be declared.
	 * @param array $field associative array with the name of the properties
	 *        of the field being declared as array indexes. Currently, the types
	 *        of supported field properties are as follows:
	 *
	 *        length
	 *            Integer value that determines the maximum length of the large
	 *            object field. If this argument is missing the field should be
	 *            declared to have the longest length allowed by the DBMS.
	 *
	 *        notnull
	 *            Boolean flag that indicates whether this field is constrained
	 *            to not be set to null.
	 * @return string DBMS specific SQL code portion that should be used to
	 *        declare the specified field.
	 * @access protected
	 */
	function _getBLOBDeclaration($name, $field)
	{
		$db =& $this->getDBInstance();
		if (PEAR::isError($db)) {
			return $db;
		}

		$notnull = empty($field['notnull']) ? '' : ' NOT NULL';
		$name = $db->quoteIdentifier($name, true);
		return $name.' '.$this->getTypeDeclaration($field).$notnull;
	}

	// }}}
	// {{{ _getBooleanDeclaration()

	/**
	 * Obtain DBMS specific SQL code portion needed to declare a boolean type
	 * field to be used in statements like CREATE TABLE.
	 *
	 * @param string $name name the field to be declared.
	 * @param array $field associative array with the name of the properties
	 *       of the field being declared as array indexes. Currently, the types
	 *       of supported field properties are as follows:
	 *
	 *       default
	 *           Boolean value to be used as default for this field.
	 *
	 *       notnullL
	 *           Boolean flag that indicates whether this field is constrained
	 *           to not be set to null.
	 * @return string DBMS specific SQL code portion that should be used to
	 *       declare the specified field.
	 * @access protected
	 */
	function _getBooleanDeclaration($name, $field)
	{
		return $this->_getDeclaration($name, $field);
	}

	// }}}
	// {{{ _getDateDeclaration()

	/**
	 * Obtain DBMS specific SQL code portion needed to declare a date type
	 * field to be used in statements like CREATE TABLE.
	 *
	 * @param string $name name the field to be declared.
	 * @param array $field associative array with the name of the properties
	 *       of the field being declared as array indexes. Currently, the types
	 *       of supported field properties are as follows:
	 *
	 *       default
	 *           Date value to be used as default for this field.
	 *
	 *       notnull
	 *           Boolean flag that indicates whether this field is constrained
	 *           to not be set to null.
	 * @return string DBMS specific SQL code portion that should be used to
	 *       declare the specified field.
	 * @access protected
	 */
	function _getDateDeclaration($name, $field)
	{
		return $this->_getDeclaration($name, $field);
	}

	// }}}
	// {{{ _getTimestampDeclaration()

	/**
	 * Obtain DBMS specific SQL code portion needed to declare a timestamp
	 * field to be used in statements like CREATE TABLE.
	 *
	 * @param string $name name the field to be declared.
	 * @param array $field associative array with the name of the properties
	 *       of the field being declared as array indexes. Currently, the types
	 *       of supported field properties are as follows:
	 *
	 *       default
	 *           Timestamp value to be used as default for this field.
	 *
	 *       notnull
	 *           Boolean flag that indicates whether this field is constrained
	 *           to not be set to null.
	 * @return string DBMS specific SQL code portion that should be used to
	 *       declare the specified field.
	 * @access protected
	 */
	function _getTimestampDeclaration($name, $field)
	{
		return $this->_getDeclaration($name, $field);
	}

	// }}}
	// {{{ _getTimeDeclaration()

	/**
	 * Obtain DBMS specific SQL code portion needed to declare a time
	 * field to be used in statements like CREATE TABLE.
	 *
	 * @param string $name name the field to be declared.
	 * @param array $field associative array with the name of the properties
	 *       of the field being declared as array indexes. Currently, the types
	 *       of supported field properties are as follows:
	 *
	 *       default
	 *           Time value to be used as default for this field.
	 *
	 *       notnull
	 *           Boolean flag that indicates whether this field is constrained
	 *           to not be set to null.
	 * @return string DBMS specific SQL code portion that should be used to
	 *       declare the specified field.
	 * @access protected
	 */
	function _getTimeDeclaration($name, $field)
	{
		return $this->_getDeclaration($name, $field);
	}

	// }}}
	// {{{ _getFloatDeclaration()

	/**
	 * Obtain DBMS specific SQL code portion needed to declare a float type
	 * field to be used in statements like CREATE TABLE.
	 *
	 * @param string $name name the field to be declared.
	 * @param array $field associative array with the name of the properties
	 *       of the field being declared as array indexes. Currently, the types
	 *       of supported field properties are as follows:
	 *
	 *       default
	 *           Float value to be used as default for this field.
	 *
	 *       notnull
	 *           Boolean flag that indicates whether this field is constrained
	 *           to not be set to null.
	 * @return string DBMS specific SQL code portion that should be used to
	 *       declare the specified field.
	 * @access protected
	 */
	function _getFloatDeclaration($name, $field)
	{
		return $this->_getDeclaration($name, $field);
	}

	// }}}
	// {{{ _getDecimalDeclaration()

	/**
	 * Obtain DBMS specific SQL code portion needed to declare a decimal type
	 * field to be used in statements like CREATE TABLE.
	 *
	 * @param string $name name the field to be declared.
	 * @param array $field associative array with the name of the properties
	 *       of the field being declared as array indexes. Currently, the types
	 *       of supported field properties are as follows:
	 *
	 *       default
	 *           Decimal value to be used as default for this field.
	 *
	 *       notnull
	 *           Boolean flag that indicates whether this field is constrained
	 *           to not be set to null.
	 * @return string DBMS specific SQL code portion that should be used to
	 *       declare the specified field.
	 * @access protected
	 */
	function _getDecimalDeclaration($name, $field)
	{
		return $this->_getDeclaration($name, $field);
	}

	// }}}
	// {{{ compareDefinition()

	/**
	 * Obtain an array of changes that may need to applied
	 *
	 * @param array $current new definition
	 * @param array  $previous old definition
	 * @return array  containing all changes that will need to be applied
	 * @access public
	 */
	function compareDefinition($current, $previous)
	{
		$type = !empty($current['type']) ? $current['type'] : null;

		if (!method_exists($this, "_compare{$type}Definition")) {
			$db =& $this->getDBInstance();
			if (PEAR::isError($db)) {
				return $db;
			}

			return $db->raiseError(MDB2_ERROR_UNSUPPORTED, null, null,
                'type "'.$current['type'].'" is not yet supported', __FUNCTION__);
		}

		if (empty($previous['type']) || $previous['type'] != $type) {
			return $current;
		}

		$change = $this->{"_compare{$type}Definition"}($current, $previous);

		if ($previous['type'] != $type) {
			$change['type'] = true;
		}

		$previous_notnull = !empty($previous['notnull']) ? $previous['notnull'] : false;
		$notnull = !empty($current['notnull']) ? $current['notnull'] : false;
		if ($previous_notnull != $notnull) {
			$change['notnull'] = true;
		}

		$previous_default = array_key_exists('default', $previous) ? $previous['default'] :
		($previous_notnull ? '' : null);
		$default = array_key_exists('default', $current) ? $current['default'] :
		($notnull ? '' : null);
		if ($previous_default !== $default) {
			$change['default'] = true;
		}

		return $change;
	}

	// }}}
	// {{{ _compareIntegerDefinition()

	/**
	 * Obtain an array of changes that may need to applied to an integer field
	 *
	 * @param array $current new definition
	 * @param array  $previous old definition
	 * @return array  containing all changes that will need to be applied
	 * @access protected
	 */
	function _compareIntegerDefinition($current, $previous)
	{
		$change = array();
		$previous_unsigned = !empty($previous['unsigned']) ? $previous['unsigned'] : false;
		$unsigned = !empty($current['unsigned']) ? $current['unsigned'] : false;
		if ($previous_unsigned != $unsigned) {
			$change['unsigned'] = true;
		}
		$previous_autoincrement = !empty($previous['autoincrement']) ? $previous['autoincrement'] : false;
		$autoincrement = !empty($current['autoincrement']) ? $current['autoincrement'] : false;
		if ($previous_autoincrement != $autoincrement) {
			$change['autoincrement'] = true;
		}
		return $change;
	}

	// }}}
	// {{{ _compareTextDefinition()

	/**
	 * Obtain an array of changes that may need to applied to an text field
	 *
	 * @param array $current new definition
	 * @param array  $previous old definition
	 * @return array  containing all changes that will need to be applied
	 * @access protected
	 */
	function _compareTextDefinition($current, $previous)
	{
		$change = array();
		$previous_length = !empty($previous['length']) ? $previous['length'] : 0;
		$length = !empty($current['length']) ? $current['length'] : 0;
		if ($previous_length != $length) {
			$change['length'] = true;
		}
		$previous_fixed = !empty($previous['fixed']) ? $previous['fixed'] : 0;
		$fixed = !empty($current['fixed']) ? $current['fixed'] : 0;
		if ($previous_fixed != $fixed) {
			$change['fixed'] = true;
		}
		return $change;
	}

	// }}}
	// {{{ _compareCLOBDefinition()

	/**
	 * Obtain an array of changes that may need to applied to an CLOB field
	 *
	 * @param array $current new definition
	 * @param array  $previous old definition
	 * @return array  containing all changes that will need to be applied
	 * @access protected
	 */
	function _compareCLOBDefinition($current, $previous)
	{
		return $this->_compareTextDefinition($current, $previous);
	}

	// }}}
	// {{{ _compareBLOBDefinition()

	/**
	 * Obtain an array of changes that may need to applied to an BLOB field
	 *
	 * @param array $current new definition
	 * @param array  $previous old definition
	 * @return array  containing all changes that will need to be applied
	 * @access protected
	 */
	function _compareBLOBDefinition($current, $previous)
	{
		return $this->_compareTextDefinition($current, $previous);
	}

	// }}}
	// {{{ _compareDateDefinition()

	/**
	 * Obtain an array of changes that may need to applied to an date field
	 *
	 * @param array $current new definition
	 * @param array  $previous old definition
	 * @return array  containing all changes that will need to be applied
	 * @access protected
	 */
	function _compareDateDefinition($current, $previous)
	{
		return array();
	}

	// }}}
	// {{{ _compareTimeDefinition()

	/**
	 * Obtain an array of changes that may need to applied to an time field
	 *
	 * @param array $current new definition
	 * @param array  $previous old definition
	 * @return array  containing all changes that will need to be applied
	 * @access protected
	 */
	function _compareTimeDefinition($current, $previous)
	{
		return array();
	}

	// }}}
	// {{{ _compareTimestampDefinition()

	/**
	 * Obtain an array of changes that may need to applied to an timestamp field
	 *
	 * @param array $current new definition
	 * @param array  $previous old definition
	 * @return array  containing all changes that will need to be applied
	 * @access protected
	 */
	function _compareTimestampDefinition($current, $previous)
	{
		return array();
	}

	// }}}
	// {{{ _compareBooleanDefinition()

	/**
	 * Obtain an array of changes that may need to applied to an boolean field
	 *
	 * @param array $current new definition
	 * @param array  $previous old definition
	 * @return array  containing all changes that will need to be applied
	 * @access protected
	 */
	function _compareBooleanDefinition($current, $previous)
	{
		return array();
	}

	// }}}
	// {{{ _compareFloatDefinition()

	/**
	 * Obtain an array of changes that may need to applied to an float field
	 *
	 * @param array $current new definition
	 * @param array  $previous old definition
	 * @return array  containing all changes that will need to be applied
	 * @access protected
	 */
	function _compareFloatDefinition($current, $previous)
	{
		return array();
	}

	// }}}
	// {{{ _compareDecimalDefinition()

	/**
	 * Obtain an array of changes that may need to applied to an decimal field
	 *
	 * @param array $current new definition
	 * @param array  $previous old definition
	 * @return array  containing all changes that will need to be applied
	 * @access protected
	 */
	function _compareDecimalDefinition($current, $previous)
	{
		return array();
	}

	// }}}
	// {{{ quote()

	/**
	 * Convert a text value into a DBMS specific format that is suitable to
	 * compose query statements.
	 *
	 * @param string $value text string value that is intended to be converted.
	 * @param string $type type to which the value should be converted to
	 * @param bool $quote determines if the value should be quoted and escaped
	 * @param bool $escape_wildcards if to escape escape wildcards
	 * @return string text string that represents the given argument value in
	 *       a DBMS specific format.
	 * @access public
	 */
	function quote($value, $type = null, $quote = true, $escape_wildcards = false)
	{
		$db =& $this->getDBInstance();
		if (PEAR::isError($db)) {
			return $db;
		}

		if (is_null($value)
		|| ($value === '' && $db->options['portability'] & MDB2_PORTABILITY_EMPTY_TO_NULL)
		) {
			if (!$quote) {
				return null;
			}
			return 'NULL';
		}

		if (is_null($type)) {
			switch (gettype($value)) {
				case 'integer':
					$type = 'integer';
					break;
				case 'double':
					// todo: default to decimal as float is quite unusual
					// $type = 'float';
					$type = 'decimal';
					break;
				case 'boolean':
					$type = 'boolean';
					break;
				case 'array':
					$value = serialize($value);
				case 'object':
					$type = 'text';
					break;
				default:
					if (preg_match('/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}$/', $value)) {
						$type = 'timestamp';
					} elseif (preg_match('/^\d{2}:\d{2}$/', $value)) {
						$type = 'time';
					} elseif (preg_match('/^\d{4}-\d{2}-\d{2}$/', $value)) {
						$type = 'date';
					} else {
						$type = 'text';
					}
					break;
			}
		} elseif (!empty($db->options['datatype_map'][$type])) {
			$type = $db->options['datatype_map'][$type];
			if (!empty($db->options['datatype_map_callback'][$type])) {
				$parameter = array('type' => $type, 'value' => $value, 'quote' => $quote, 'escape_wildcards' => $escape_wildcards);
				return call_user_func_array($db->options['datatype_map_callback'][$type], array(&$db, __FUNCTION__, $parameter));
			}
		}

		if (!method_exists($this, "_quote{$type}")) {
			return $db->raiseError(MDB2_ERROR_UNSUPPORTED, null, null,
                'type not defined: '.$type, __FUNCTION__);
		}
		$value = $this->{"_quote{$type}"}($value, $quote, $escape_wildcards);
		if ($quote && $escape_wildcards && $db->string_quoting['escape_pattern']
		&& $db->string_quoting['escape'] !== $db->string_quoting['escape_pattern']
		) {
			$value.= $this->patternEscapeString();
		}
		return $value;
	}

	// }}}
	// {{{ _quoteInteger()

	/**
	 * Convert a text value into a DBMS specific format that is suitable to
	 * compose query statements.
	 *
	 * @param string $value text string value that is intended to be converted.
	 * @param bool $quote determines if the value should be quoted and escaped
	 * @param bool $escape_wildcards if to escape escape wildcards
	 * @return string text string that represents the given argument value in
	 *       a DBMS specific format.
	 * @access protected
	 */
	function _quoteInteger($value, $quote, $escape_wildcards)
	{
		return (int)$value;
	}

	// }}}
	// {{{ _quoteText()

	/**
	 * Convert a text value into a DBMS specific format that is suitable to
	 * compose query statements.
	 *
	 * @param string $value text string value that is intended to be converted.
	 * @param bool $quote determines if the value should be quoted and escaped
	 * @param bool $escape_wildcards if to escape escape wildcards
	 * @return string text string that already contains any DBMS specific
	 *       escaped character sequences.
	 * @access protected
	 */
	function _quoteText($value, $quote, $escape_wildcards)
	{
		if (!$quote) {
			return $value;
		}

		$db =& $this->getDBInstance();
		if (PEAR::isError($db)) {
			return $db;
		}

		$value = $db->escape($value, $escape_wildcards);
		return "'".$value."'";
	}

	// }}}
	// {{{ _readFile()

	/**
	 * Convert a text value into a DBMS specific format that is suitable to
	 * compose query statements.
	 *
	 * @param string $value text string value that is intended to be converted.
	 * @return string text string that represents the given argument value in
	 *       a DBMS specific format.
	 * @access protected
	 */
	function _readFile($value)
	{
		$close = false;
		if (preg_match('/^(\w+:\/\/)(.*)$/', $value, $match)) {
			$close = true;
			if ($match[1] == 'file://') {
				$value = $match[2];
			}
			$value = @fopen($value, 'r');
		}

		if (is_resource($value)) {
			$db =& $this->getDBInstance();
			if (PEAR::isError($db)) {
				return $db;
			}

			$fp = $value;
			$value = '';
			while (!@feof($fp)) {
				$value.= @fread($fp, $db->options['lob_buffer_length']);
			}
			if ($close) {
				@fclose($fp);
			}
		}

		return $value;
	}

	// }}}
	// {{{ _quoteLOB()

	/**
	 * Convert a text value into a DBMS specific format that is suitable to
	 * compose query statements.
	 *
	 * @param string $value text string value that is intended to be converted.
	 * @param bool $quote determines if the value should be quoted and escaped
	 * @param bool $escape_wildcards if to escape escape wildcards
	 * @return string text string that represents the given argument value in
	 *       a DBMS specific format.
	 * @access protected
	 */
	function _quoteLOB($value, $quote, $escape_wildcards)
	{
		$value = $this->_readFile($value);
		return $this->_quoteText($value, $quote, $escape_wildcards);
	}

	// }}}
	// {{{ _quoteCLOB()

	/**
	 * Convert a text value into a DBMS specific format that is suitable to
	 * compose query statements.
	 *
	 * @param string $value text string value that is intended to be converted.
	 * @param bool $quote determines if the value should be quoted and escaped
	 * @param bool $escape_wildcards if to escape escape wildcards
	 * @return string text string that represents the given argument value in
	 *       a DBMS specific format.
	 * @access protected
	 */
	function _quoteCLOB($value, $quote, $escape_wildcards)
	{
		return $this->_quoteLOB($value, $quote, $escape_wildcards);
	}

	// }}}
	// {{{ _quoteBLOB()

	/**
	 * Convert a text value into a DBMS specific format that is suitable to
	 * compose query statements.
	 *
	 * @param string $value text string value that is intended to be converted.
	 * @param bool $quote determines if the value should be quoted and escaped
	 * @param bool $escape_wildcards if to escape escape wildcards
	 * @return string text string that represents the given argument value in
	 *       a DBMS specific format.
	 * @access protected
	 */
	function _quoteBLOB($value, $quote, $escape_wildcards)
	{
		return $this->_quoteLOB($value, $quote, $escape_wildcards);
	}

	// }}}
	// {{{ _quoteBoolean()

	/**
	 * Convert a text value into a DBMS specific format that is suitable to
	 * compose query statements.
	 *
	 * @param string $value text string value that is intended to be converted.
	 * @param bool $quote determines if the value should be quoted and escaped
	 * @param bool $escape_wildcards if to escape escape wildcards
	 * @return string text string that represents the given argument value in
	 *       a DBMS specific format.
	 * @access protected
	 */
	function _quoteBoolean($value, $quote, $escape_wildcards)
	{
		return ($value ? 1 : 0);
	}

	// }}}
	// {{{ _quoteDate()

	/**
	 * Convert a text value into a DBMS specific format that is suitable to
	 * compose query statements.
	 *
	 * @param string $value text string value that is intended to be converted.
	 * @param bool $quote determines if the value should be quoted and escaped
	 * @param bool $escape_wildcards if to escape escape wildcards
	 * @return string text string that represents the given argument value in
	 *       a DBMS specific format.
	 * @access protected
	 */
	function _quoteDate($value, $quote, $escape_wildcards)
	{
		if ($value === 'CURRENT_DATE') {
			$db =& $this->getDBInstance();
			if (PEAR::isError($db)) {
				return $db;
			}
			if (isset($db->function) && is_a($db->function, 'MDB2_Driver_Function_Common')) {
				return $db->function->now('date');
			}
			return 'CURRENT_DATE';
		}
		return $this->_quoteText($value, $quote, $escape_wildcards);
	}

	// }}}
	// {{{ _quoteTimestamp()

	/**
	 * Convert a text value into a DBMS specific format that is suitable to
	 * compose query statements.
	 *
	 * @param string $value text string value that is intended to be converted.
	 * @param bool $quote determines if the value should be quoted and escaped
	 * @param bool $escape_wildcards if to escape escape wildcards
	 * @return string text string that represents the given argument value in
	 *       a DBMS specific format.
	 * @access protected
	 */
	function _quoteTimestamp($value, $quote, $escape_wildcards)
	{
		if ($value === 'CURRENT_TIMESTAMP') {
			$db =& $this->getDBInstance();
			if (PEAR::isError($db)) {
				return $db;
			}
			if (isset($db->function) && is_a($db->function, 'MDB2_Driver_Function_Common')) {
				return $db->function->now('timestamp');
			}
			return 'CURRENT_TIMESTAMP';
		}
		return $this->_quoteText($value, $quote, $escape_wildcards);
	}

	// }}}
	// {{{ _quoteTime()

	/**
	 * Convert a text value into a DBMS specific format that is suitable to
	 *       compose query statements.
	 *
	 * @param string $value text string value that is intended to be converted.
	 * @param bool $quote determines if the value should be quoted and escaped
	 * @param bool $escape_wildcards if to escape escape wildcards
	 * @return string text string that represents the given argument value in
	 *       a DBMS specific format.
	 * @access protected
	 */
	function _quoteTime($value, $quote, $escape_wildcards)
	{
		if ($value === 'CURRENT_TIME') {
			$db =& $this->getDBInstance();
			if (PEAR::isError($db)) {
				return $db;
			}
			if (isset($db->function) && is_a($db->function, 'MDB2_Driver_Function_Common')) {
				return $db->function->now('time');
			}
			return 'CURRENT_TIME';
		}
		return $this->_quoteText($value, $quote, $escape_wildcards);
	}

	// }}}
	// {{{ _quoteFloat()

	/**
	 * Convert a text value into a DBMS specific format that is suitable to
	 * compose query statements.
	 *
	 * @param string $value text string value that is intended to be converted.
	 * @param bool $quote determines if the value should be quoted and escaped
	 * @param bool $escape_wildcards if to escape escape wildcards
	 * @return string text string that represents the given argument value in
	 *       a DBMS specific format.
	 * @access protected
	 */
	function _quoteFloat($value, $quote, $escape_wildcards)
	{
		if (preg_match('/^(.*)e([-+])(\d+)$/i', $value, $matches)) {
			$decimal = $this->_quoteDecimal($matches[1], $quote, $escape_wildcards);
			$sign = $matches[2];
			$exponent = str_pad($matches[3], 2, '0', STR_PAD_LEFT);
			$value = $decimal.'E'.$sign.$exponent;
		} else {
			$value = $this->_quoteDecimal($value, $quote, $escape_wildcards);
		}
		return $value;
	}

	// }}}
	// {{{ _quoteDecimal()

	/**
	 * Convert a text value into a DBMS specific format that is suitable to
	 * compose query statements.
	 *
	 * @param string $value text string value that is intended to be converted.
	 * @param bool $quote determines if the value should be quoted and escaped
	 * @param bool $escape_wildcards if to escape escape wildcards
	 * @return string text string that represents the given argument value in
	 *       a DBMS specific format.
	 * @access protected
	 */
	function _quoteDecimal($value, $quote, $escape_wildcards)
	{
		$value = (string)$value;
		if (preg_match('/[^.0-9]/', $value)) {
			if (strpos($value, ',')) {
				// 1000,00
				if (!strpos($value, '.')) {
					// convert the last "," to a "."
					$value = strrev(str_replace(',', '.', strrev($value)));
					// 1.000,00
				} elseif (strpos($value, '.') && strpos($value, '.') < strpos($value, ',')) {
					$value = str_replace('.', '', $value);
					// convert the last "," to a "."
					$value = strrev(str_replace(',', '.', strrev($value)));
					// 1,000.00
				} else {
					$value = str_replace(',', '', $value);
				}
			}
		}
		return $value;
	}

	// }}}
	// {{{ writeLOBToFile()

	/**
	 * retrieve LOB from the database
	 *
	 * @param resource $lob stream handle
	 * @param string $file name of the file into which the LOb should be fetched
	 * @return mixed MDB2_OK on success, a MDB2 error on failure
	 * @access protected
	 */
	function writeLOBToFile($lob, $file)
	{
		$db =& $this->getDBInstance();
		if (PEAR::isError($db)) {
			return $db;
		}

		if (preg_match('/^(\w+:\/\/)(.*)$/', $file, $match)) {
			if ($match[1] == 'file://') {
				$file = $match[2];
			}
		}

		$fp = @fopen($file, 'wb');
		while (!@feof($lob)) {
			$result = @fread($lob, $db->options['lob_buffer_length']);
			$read = strlen($result);
			if (@fwrite($fp, $result, $read) != $read) {
				@fclose($fp);
				return $db->raiseError(MDB2_ERROR, null, null,
                    'could not write to the output file', __FUNCTION__);
			}
		}
		@fclose($fp);
		return MDB2_OK;
	}

	// }}}
	// {{{ _retrieveLOB()

	/**
	 * retrieve LOB from the database
	 *
	 * @param array $lob array
	 * @return mixed MDB2_OK on success, a MDB2 error on failure
	 * @access protected
	 */
	function _retrieveLOB(&$lob)
	{
		if (is_null($lob['value'])) {
			$lob['value'] = $lob['resource'];
		}
		$lob['loaded'] = true;
		return MDB2_OK;
	}

	// }}}
	// {{{ readLOB()

	/**
	 * Read data from large object input stream.
	 *
	 * @param resource $lob stream handle
	 * @param string $data reference to a variable that will hold data
	 *                          to be read from the large object input stream
	 * @param integer $length    value that indicates the largest ammount ofdata
	 *                          to be read from the large object input stream.
	 * @return mixed the effective number of bytes read from the large object
	 *                      input stream on sucess or an MDB2 error object.
	 * @access public
	 * @see endOfLOB()
	 */
	function _readLOB($lob, $length)
	{
		return substr($lob['value'], $lob['position'], $length);
	}

	// }}}
	// {{{ _endOfLOB()

	/**
	 * Determine whether it was reached the end of the large object and
	 * therefore there is no more data to be read for the its input stream.
	 *
	 * @param array $lob array
	 * @return mixed true or false on success, a MDB2 error on failure
	 * @access protected
	 */
	function _endOfLOB($lob)
	{
		return $lob['endOfLOB'];
	}

	// }}}
	// {{{ destroyLOB()

	/**
	 * Free any resources allocated during the lifetime of the large object
	 * handler object.
	 *
	 * @param resource $lob stream handle
	 * @access public
	 */
	function destroyLOB($lob)
	{
		$lob_data = stream_get_meta_data($lob);
		$lob_index = $lob_data['wrapper_data']->lob_index;
		fclose($lob);
		if (isset($this->lobs[$lob_index])) {
			$this->_destroyLOB($this->lobs[$lob_index]);
			unset($this->lobs[$lob_index]);
		}
		return MDB2_OK;
	}

	// }}}
	// {{{ _destroyLOB()

	/**
	 * Free any resources allocated during the lifetime of the large object
	 * handler object.
	 *
	 * @param array $lob array
	 * @access private
	 */
	function _destroyLOB(&$lob)
	{
		return MDB2_OK;
	}

	// }}}
	// {{{ implodeArray()

	/**
	 * apply a type to all values of an array and return as a comma seperated string
	 * useful for generating IN statements
	 *
	 * @access public
	 *
	 * @param array $array data array
	 * @param string $type determines type of the field
	 *
	 * @return string comma seperated values
	 */
	function implodeArray($array, $type = false)
	{
		if (!is_array($array) || empty($array)) {
			return 'NULL';
		}
		if ($type) {
			foreach ($array as $value) {
				$return[] = $this->quote($value, $type);
			}
		} else {
			$return = $array;
		}
		return implode(', ', $return);
	}

	// }}}
	// {{{ matchPattern()

	/**
	 * build a pattern matching string
	 *
	 * EXPERIMENTAL
	 *
	 * WARNING: this function is experimental and may change signature at
	 * any time until labelled as non-experimental
	 *
	 * @access public
	 *
	 * @param array $pattern even keys are strings, odd are patterns (% and _)
	 * @param string $operator optional pattern operator (LIKE, ILIKE and maybe others in the future)
	 * @param string $field optional field name that is being matched against
	 *                  (might be required when emulating ILIKE)
	 *
	 * @return string SQL pattern
	 */
	function matchPattern($pattern, $operator = null, $field = null)
	{
		$db =& $this->getDBInstance();
		if (PEAR::isError($db)) {
			return $db;
		}

		$match = '';
		if (!is_null($operator)) {
			$operator = strtoupper($operator);
			switch ($operator) {
				// case insensitive
				case 'ILIKE':
					if (is_null($field)) {
						return $db->raiseError(MDB2_ERROR_UNSUPPORTED, null, null,
                        'case insensitive LIKE matching requires passing the field name', __FUNCTION__);
					}
					$db->loadModule('Function', null, true);
					$match = $db->function->lower($field).' '.'LIKE ';
					break;
					// case sensitive
				case 'LIKE':
					$match = is_null($field) ? 'LIKE ' : $field.' LIKE ';
					break;
				default:
					return $db->raiseError(MDB2_ERROR_UNSUPPORTED, null, null,
                    'not a supported operator type:'. $operator, __FUNCTION__);
			}
		}
		$match.= "'";
		foreach ($pattern as $key => $value) {
			if ($key % 2) {
				$match.= $value;
			} else {
				if ($operator === 'ILIKE') {
					$value = strtolower($value);
				}
				$match.= $db->escapePattern($db->escape($value));
			}
		}
		$match.= "'";
		$match.= $this->patternEscapeString();
		return $match;
	}

	// }}}
	// {{{ patternEscapeString()

	/**
	 * build string to define pattern escape character
	 *
	 * EXPERIMENTAL
	 *
	 * WARNING: this function is experimental and may change signature at
	 * any time until labelled as non-experimental
	 *
	 * @access public
	 *
	 * @return string define pattern escape character
	 */
	function patternEscapeString()
	{
		return '';
	}

	// }}}
	// {{{ mapNativeDatatype()

	/**
	 * Maps a native array description of a field to a MDB2 datatype and length
	 *
	 * @param array  $field native field description
	 * @return array containing the various possible types, length, sign, fixed
	 * @access public
	 */
	function mapNativeDatatype($field)
	{
		$db =& $this->getDBInstance();
		if (PEAR::isError($db)) {
			return $db;
		}

		return $db->raiseError(MDB2_ERROR_UNSUPPORTED, null, null,
            'method not implemented', __FUNCTION__);
	}

	// }}}
	// {{{ mapPrepareDatatype()

	/**
	 * Maps an mdb2 datatype to mysqli prepare type
	 *
	 * @param string $type
	 * @return string
	 * @access public
	 */
	function mapPrepareDatatype($type)
	{
		$db =& $this->getDBInstance();
		if (PEAR::isError($db)) {
			return $db;
		}

		if (!empty($db->options['datatype_map'][$type])) {
			$type = $db->options['datatype_map'][$type];
			if (!empty($db->options['datatype_map_callback'][$type])) {
				$parameter = array('type' => $type);
				return call_user_func_array($db->options['datatype_map_callback'][$type], array(&$db, __FUNCTION__, $parameter));
			}
		}

		return $type;
	}
	}

	?>